A 10-year-old mildly heavy-set Caucasian girl presents with increasing pain in the region of her right hip. No history of trauma, fever, prior arthropathy, bleeding diathesis, or other contributing history is noted.
What’s the most likely cause of this young girl’s symptoms?
a) iliac horn syndrome (Fong disease/nail-patella syndrome)
b) slipped capital femoral epiphysis (SCFE)
c) tumoral calcinosis
d) congenital dysplasia of the hip (CDH)
e) avulsion fracture anterior inferior iliac spine (ASIS)
b) slipped capital femoral epiphysis — SCFE
The radiographs shown (Fig. 1A & 1B) reveal a subtle postero-medial slippage of the right femoral head upon the right femoral shaft, at the level of the growth plate. The appearance is quite subtle on the AP view (Fig. 1A) and can be appreciated if you draw a mental line parallel to the superior edge of the cortex of the femoral neck extending toward the head. That line should transect some portion of the femoral capital epiphysis (femoral head) along its superior aspect, as it would in this patient on the left side (remember that, by convention, the left hip is on the right side of the image as you view it, and the right hip on the left). On the right, the line would barely touch the femoral head superior cortical margin. The slippage is most evident on the right hip oblique view (Fig. 1B), where the capital epiphysis can be seen postero-medial to the neck component (and that imaginary line would come nowhere near the femoral head cortex). See also Figure 2 below, which pictorially demonstrates grading of SCFE severity.
Slipped capital femoral epiphysis (SCFE) is a pediatric disease condition that describes the slow separation and slippage of the femoral head growth plate, and associated femoral head, from the subjacent femoral metaphysis and shaft. The disease is a form of Salter-Harris Type I injury. The femoral head typically shifts posterior and medial, in relation to the femoral shaft, as in the case shown. The condition leads to reduced range of motion along with hip and referred knee pain. The exact cause is unknown but SCFE is much more commonly seen in cases of childhood obesity and affects boys twice as often as girls. The slip usually occurs between the ages of 12-15 years in boys, 10-13 years in girls. The disease can develop in the contralateral hip in up to 25% of patients, within 18 months of the original diagnosis. If undiscovered, the disease can lead to premature arthritis or femoral head necrosis. Most cases are treated surgically, with excellent results. A few cases (non-operative candidates) may be treated with a hip spica cast as an alternative but it’s not the primary treatment of choice.
If plain x-rays are normal or inconclusive and there is still high clinical suspicion of SCFE, MRI of the hips can be performed to further evaluate. Although a CT scan would arguably be a better test to accurately assess the regional bony anatomy, the MRI is preferred due to the lack of ionizing radiation (as occurs with CT) in imaging the pediatric population.
In iliac horn syndrome, there are prominent osseous projections evident from the superolateral aspects of the iliac bones bilaterally, looking like an animal’s horns, which are pathognomonic for the disease. The condition is also known as Fong’s disease, or nail-patella syndrome and is also associated with dystrophic finger and toe nails, and absent or hypoplastic patellae. These patients may also suffer from renal disorders such as stones, reflux, nephritic syndrome and failure. Such iliac horns are not present in our case. Tumoral calcinosis is a benign familial condition of phosphate metabolic dysfunction characterized by solitary or multiple painless periarticular masses of dystrophic soft tissue calcification, which can reach extraordinary sizes. The disease is seen with significantly higher incidence in patients of African descent for reasons unknown. No soft tissue calcification is present in this case and as such this condition should not be considered. Congenital dysplasia of the hip (CDH), also known as developmental dysplasia of the hip (DDH), and formerly known as congenital dislocation of the hip, is a fairly common condition occurring in newborns whereby the acetabular angle is steep, resulting in temporary or permanent instability of the hip joint with potential for hip subluxation, dislocation and premature arthritis. The imaging modality of choice these days for early diagnosis of CDH is neonatal hip ultrasound, which can easily visualize the unossified femoral heads in the neonate and young infants, and can assess hip stability and potential for subluxability in real time. X-rays show the changes of CDH rather late and should not be utilized in the diagnosis in young children. The advanced age of this child, the past history of normal development and ambulation, and the normal appearing acetabular cup regions rule out the diagnosis of CDH in the case presented. There’s no fracture present in the case above and as such, the choice of avulsion fracture of the anterior inferior iliac spine (ASIS) should not be considered.
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